There is no reason that "potential" racers cannot be allowed to fly with whatever engine they happen to have. The CD would simply need to verify the subject engine doesn't have a performance advantage and let them fly. In fact the APRA Quickee Sport rules that the current 424 was based on has a clause that allows this:

*4.3 First Time Pilots. A Sportsman pilot entering his/her first race may enter the event with a different engine than those listed above at the discretion of the CD. The entered engine may not provide any performance advantage relative to the normal Quickie Sport entries. This exception may apply to the pilot for two races only.

I fought strongly to not make the engine list "National" because of how difficult it is to tightly manage the rules with a 2 year (3 years at the time) rules cycle. At the 424 level, it is my opinion that each area of the country should adapt to whatever is best for their area. I was outvoted and then asked to run the engine approval committee because of my years of experience managing the topic. The decision was made that the engine to start the list with was the TT40 because it is so widely used for lots of reasons.

The primary criteria for the list is performance, but not the only one. Stability of the company, variability of versions of the engines and the parts supplied for the engines is also considered. We have been very fortunate that the TT40 is such a good product that is relatively consistent, durable and reliable (especially the last few years), and they are strong company who has done a good job of keeping the supply of the engines strong. There was one period where the supply dried up for a few months several years ago, but they worked through that. WE ABSOLUTELY CANNOT ALLOW AN ENGINE ON THE LIST THAT WILL OBSOLETE THE THUNDER TIGER 40!!!! It would be the beginning of the end for pylon as we know it. We've had the "what if TT goes away" arguement thrown at us several times over the years. If that happens, there are ways to get things done quickly if it is deemed a true emergency for the event. As long as TT is selling engines, we do not have an emergency. If that emergency happens, there are a TON of TT's out there that will keep things going while we make a good, well thought out decision and take the necessary steps. Will people panic, YES. Can we let the panic force us to make a bad decision, NO. Till TT goes out of business we'll manage the event to maintain the stability we have enjoyed for quite a few years.

At the time the "list" was added to the AMA 424 event, the ST40 was unavailable. Believe it or not we used to have the ST40 on the APRA list. Good engine, but there were lots of problems with mufflers (three different ones) and lots of variation in the engines and parts. It got bad when they started shipping with a muffler that made the engine quite a bit slower than the previous muffler. Now a guy has to buy an engine and hope he can find a dusty version of the previous "faster" muffler to be competitive. Some inventive racers found that the cylinders sold as spares at the time had different and a LOT faster timing than the cylinders installed in the production engines. You can imagine the BS that caused!!!! That problem could still surface. It was a very durable engine in a lot of ways and we all know how good an ST carb is (or at least used to be).

We have tested the Evo 40. Horizon Hobby sent me four new engines to test. The are a good engine that are surprizingly consistent, but they're on average 1200 rpm below the Thunder Tiger. Many people are dismissing the thought that this is a problem. As Gary Schmidt said very well on the forum recently, In the 17 year experience managing the APRA class here on the West Coast, it IS a problem, but it is a problem that a CD can easily deal with for first timers by using a tach and verifying the engine brand the new racer has will not have an advantage and let them fly. Adding an engine to the list was interpreted as an endorsement of the product for the class. There were some pissed off racers who found out that the engine they just bought, because it was on the APRA list, wasn't competitive at all. If you haven't been there and been through that, of course you think this wouldn't be a problem, but is definitely was. I gave Horizon feedback on how I felt they could make the engine competitive. They said thanks but have chosen to not take that approach. I respect that. I am sure it didn't make good business sense for them. With a little work, it could be a good engine for the list.

The Magnum 40 was tested a couple of years ago. I was given two new engines to test and allowed to test a few more that belonged to other modelers in CA. The engine is well made, but was found to vary quite a bit in performance from engine to engine. A few were noticably down from the TT40 most were similar, and a few BLEW AWAY the TT40. A LOT!!! That kind of variability would kill the event. Having to buy 5 to 10 engines to get one or two of the killers when everybody has several TT40's would be a BIG problem. That engine will not be added to the list. Good engine, but it would definitely "upset the apple cart".

I was given MVVS engines to test several years ago. The version sent to me was a very nice engine that was well made, but it wasn't even close to the TT40 in performance. About 1500 down with the 9-6. THE VERSION SENT TO ME. Further research and testing of engines that friends in my club had showed that there were several different configurations of carb bore and muffler. The parts were interchangeable with the parts in the engines I was supplied. The engines with the larger carb bore and different muffler BLEW AWAY the TT40. They're as strong as a Rossi. It would have created a CD's nightmare to control. Again, great engine, but one that would have had detrimental effects on the event.

Now, with all this said, are we open to investigating other engines? ABSOLUTELY. Trouble is, the manufacturers have not been beating our doors down to supply us engines to be tested. We would need at least 4 examples of a prospective engine. They will be inspected for quality and potential problems. Then they will be broken in carefully, and tested on the bench with not only a 9-6, but two different levels of unload props. One engine tested (I won't say which) didn't show the higher performance than the TT40 until I installed the lightest unload prop. Then at least one will be installed on an airplane and flight tested. We will then compare this data to two TT40's that I have. One is on the high side of average, the other is quite strong. This way we eliminate the variability of fuel and weather conditions. Only then can we be sure we have an appropriate engine for the class.

Remember there should be no reason that a CD can't apply common sense and let a new racer use whatever engine he has, as long as it doesn't have a performance advantage over the "approved" engines. Down the road, if he sticks with the sport, he'll want to get one of the "approved" competitive engine. Some of you might not agree with me on this, but it comes from 17 years of experience maintaining the rules that became the basis for the current version of 424. We know how to keep the stability. Our sport cannot survive the loss of it.

Jim Allen
AMA 424 Engine Sub-Committee Chair.